National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 17bSeptember 2015
NIST Standard Reference Database 101
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XIXIndex of properties
XXH-bond dimers
XXIOddities

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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for PO (Phosphorus monoxide)

Experimental Ionization Energy is 8.39 ± 0.01 eV
Please note! These calculated ionizataion energies have the vibrational zero-point energy (zpe) included, but the zpe has NOT been scaled. Click on an entry for more details, including the ionization energy with a scaled zpe.
Original data displayed. Press to display differences.
Differences displayed. Press to display original data.

Ionization Energies in eV
Methods with predefined basis sets
semi-empirical AM1  
PM3  
PM6  
composite G2 8.392
G3 8.485
G3B3 8.770
G4 8.539
CBS-Q 8.386

Ionization Energies in eV
Methods with standard basis sets
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 4.844 9.069 7.979 9.530 7.987 7.980 8.143 7.983 7.983 8.006 8.138 8.065 8.112 8.134 8.253 8.177 8.153
density functional LSDA 5.600 8.620 8.620 9.282 8.783 8.783 8.985 8.829 8.829 8.768   8.805 8.907   9.028 8.973  
SVWN   8.930     8.783   8.985       8.956            
BLYP 4.995 8.272 7.990 8.642 8.167 8.167 8.399 8.216 8.216 8.155   8.174 8.295        
B1B95 5.341 5.281 8.161 8.893 8.287 8.355 8.534 8.310 8.310 8.268   8.389 8.374   8.508 8.441  
B3LYP 5.341 8.616 8.270 8.986 8.423 8.423 8.626 8.454 8.454 8.407 8.589 8.445 8.535 8.565 8.674 8.610 8.591
B3LYPultrafine         8.423                        
B3PW91 5.444 8.705 8.352 9.046 8.477 8.477 8.649 8.503 8.503 8.466   8.516 8.579        
mPW1PW91 5.458 8.724 8.357 9.073 8.485 8.485 8.659 8.511 8.511 8.475   8.521 8.583        
M06-2X     8.281   8.281                        
PBEPBE 5.150 8.450 8.160 8.801 8.319 8.319 8.524 8.360 8.360 8.313   8.339 8.435        
PBE1PBE         8.450                        
HSEh1PBE   8.678     8.445   8.622           8.547        
TPSSh         8.446   8.618     8.441     8.554        
wB97X-D     8.274   8.393       8.421       8.474     8.533  
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Moller Plesset perturbation MP2 3.093 5.875 7.335 6.054 7.370 7.370 7.651 7.412 7.412 7.870 7.573 7.300 8.001 8.120 8.035 8.128 8.169
MP2=FULL 3.079 5.865 7.327 6.046 7.367 7.367 7.647 7.412 7.412 7.866   7.302 7.996 8.112     8.159
MP3         7.778                        
MP3=FULL         7.774                        
MP4   3.377     7.112       7.127       8.175        
B2PLYP         8.084               8.294        
Configuration interaction CID         7.758     7.800                  
CISD         7.719                        
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Quadratic configuration interaction QCISD   7.830 7.508 8.225 7.769 7.769 7.964 7.766 7.766 8.105   7.882 8.236        
QCISD(T)         7.736                        
Coupled Cluster CCD   7.137 7.572 7.520 7.677 7.677 7.935 7.725 7.725 8.117   7.644 8.250   8.056 8.362  
CCSD         7.817                        
CCSD(T)                         8.216        
CCSD(T)=FULL         7.725                        
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ

Ionization Energies in eV
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 9.704 8.176 9.515 8.131 9.606 9.353
density functional B3LYP 9.220 8.590 9.053 8.543 9.118 8.960
Moller Plesset perturbation MP2 6.274 7.517 6.231 7.501 7.799 6.235
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.